ArtifexSoftware/mupdf — reverse-engineered prompt

I want this repo turned into a working lightweight document viewer and converter I can run locally. It should build cleanly and let me open and render PDF, XPS, and ebook style documents, then convert or export pages in a practical way. Please wire up whatever is missing so there is an easy way to compile it, run it, and try it on sample files, with sensible defaults and clear commands. If there are multiple ways to build it, pick the simplest reliable path and make sure the main viewing and conversion flow actually works.

Please also add a short getting started guide for a normal person that explains how to build it, launch it, and use the core features, plus any important platform specific gotchas. If basic smoke checks make sense, add them so I can quickly tell whether the build succeeded. Keep the project lightweight and focused on fast document viewing and conversion. Look up the current docs online if you need to.